It might not be exactly what you are looking for, but git-bug[1] is encoding data into regular git objects, with merges and conflict resolution. I'm mentioning this because the hard part is providing an ordering of events. Once you have that you can store and recreate whatever state you want.
This branch[2] I'm almost done with remove the purely linear branch constraint and allow to use full DAGs (that is, concurrent edition) and still provide a good ordering.
